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We’re keeping an eye on the Japan earthquake story as it evolves. Here’s the latest:
11 April 2011 : 7.1 aftershock earthquake rattles north-east Japan shortly after families and friends’ of the 28,000 plus dead or missing pause to remember their loved ones. A tsunami warning was triggered (although waves only as high as 3 feet (as opposed to 30 feet during the 9.0 earthquake are expected), and the Fukushima nuclear plant was evacuated. The quake epicentre was right in the middle of Fukushima prefecture, and only 6 miles deep. The evacuation zone has been extended to 40km.
Honshu Japan is Rocked by a 9.0 Earthquake on March 11th, 2011
On March 11th, 2011 the East Coast of Honshu Japan was rocked by an earthquake that measured in at a magnitude of 9.0. This Earth shattering quake was just the beginning of things to come for Japan as a series of tragic events would soon begin to unfold as a result of the initial quake. As Japanese citizens struggled to overcome the damage that the incredible quake caused there was little time for rescue efforts to unfold as a tsunami, spawned by the giant earthquake rolled across the shorelines bringing with it waves of immense proportions. As the tsunami swallowed up the East Coast of Japan, leaving in its wake nothing but death and destruction, those who were fortunate enough to make it out alive held on for dear life as Japan launched rescue efforts. The overall devastation caused by the combination of the record breaking quake and the following tsunami would be enough to cause any number of people to turn tail and run; however, the Japanese have done no such thing and they continue to diligently work towards saving their country from any further devastation.
Earthquakes in Japan
Japan is a country that is used to seismic activity; in fact, earthquakes become such a common part of life for the Japanese that schools hold drills and instructional courses on how to stay safe during the event of an earthquake. These frequently occurring earthquakes are down to the geographic location of Japan as it sits on an area of the Earth that sees the meeting of various continental and oceanic plates. As these tectonic plates move they cause earthquake activity and as plates move underneath or rather close to the ocean these quakes often produce tsunamis. As tectonic plates move they can cause something of a ripple effect from the momentum of the movement in the water and this ripple rapidly causes waves which grow in size and intensity as they travel.
The Largest Historical Quake in Japan: 1923
The 1923 Great Kanto Earthquake
Before the quake of 2011 the largest historical quake in Japan occurred in 1923 and is referred to as the “Great Kanto earthquake.” This quake struck on September 1, 1923 with a force of 7.9 on the Richter scale…a force that now seems minimal in comparison to the 9.0 quake that occurred on March 11, 2011. While the 1923 quake may seem trivial in comparison to recent events, it was one of the biggest historic natural disasters in the nation as the 4 to 10 minute quake spawned the death of thousands. The quake in combination with a typhoon that swept in to the area, taking advantage of the significant drop in atmospheric pressure, has been named the cause of death in some 99,300 people with another 43,000 going missing. Certainly these numbers overshadow current death tolls of just over 11,000 in the 2011 quake in Japan; however, the current disaster is far from over and final death tolls having yet to be made.
The 1923 quake is credited with such a significant loss of life for a number of reasons but namely due to the fact that it hit during lunch time when a large number of people were utilizing fire to cook. As the quake took hold of the cities fires quickly broke out and began to spread as the winds spawned by the typhoon that was rolling in picked up the flames. One of the most horrific aspects of this particular quake, aside from the astronomical death tolls was the manner in which many individuals died as they became trapped as their feet were anchored in melting tarmac. Many individuals lost their lives on that fateful day with the largest single event being the death of 38,000 people who were caught in a fire whirl in Rikugun Honju Hifukusho. Fire was the largest culprit in the many thousands of deaths that were caused by the 1923 earthquake; however, many other individuals experienced death due to landslides and a tsunami that followed the quake that brought with it 33 foot tall waves. This string of disasters left behind it nearly 100,000 deaths, nearly 50,000 missing people, a near one billion dollars in damage and the punches kept on coming as the nation was rocked by fifty seven aftershocks.
The New Largest Quake in Japan: 2011
The recent earthquake that struck Japan measured up as the largest to date initially being tagged as an 8.9 on the Richter scale but it was soon upgraded to a 9.0 on the Richter scale. This quake rolled in to Japan at a quarter to six in the morning of Friday, March 11th UCT or a quarter to three in the afternoon local time. Just two days earlier the east coast of Honshu, Japan felt a magnitude 7.2 quake at a quarter to twelve local time but no one could have predicted that the 7.2 quake was only a sign of things to come. On the morning of March, 11th the 9.0 quake shook the country and soon to follow was a 23 foot tsunami that swept over the coast destroying entire cities. The eastern and northeastern coasts were particularly hard hit but the quake was of such magnitude and the tsunami was of such force that the after effects are being felt all over the country. It is currently estimated that over 12,000 individuals are dead or missing but at this point in time that figure is not believed to be final. The outlook may be grim but there are still some stories of hope trickling through the devastation as news breaks tell of infants who have been rescued from under rubble and one elderly citizen who was found clinging to the roof of his house in the ocean, he had been there for two days before being rescued.
How Did Such A Large Quake Occur?
Understanding Tectonic Plates
To understand how the largest Earthquake ever measured in Japan came about it is first important to understand how exactly earthquakes occur in the first place. The Earth is made up of a variety of tectonic plates which are also referred to as lithospheric plates. These plates are made of solid rock and vary in size and shape. These plates float on the asthenosphere of the Earth’s mantle. In all there are ten major tectonic plates and there are also multiple minor plates. Plates are considered either continental or oceanic depending upon where they lay and each is comprised of a different type of rock formulation. The plates that make up the continental plates are made from granitic rocks that are particularly light and oceanic plates are made from basaltic rock which is heavier. The difference in weight in these two types of plate is made up for by differences in thickness in the plates. As the mantle that lies underneath the tectonic plates circulates the plates move slowly. The plates that form the bottom of the Earth’s crust are constantly moving very slowly in a process that is referred to as tectonic drift. The drifting plates are what shape the world’s continents as can be seen in the transformation of the Earth’s face from the once supercontinent of Pangaea. As these plates move they can either run up against each other or pull away from each other and it is this movement that causes earthquakes.
How Do Earthquakes Cause Tsunamis?
Tsunamis are series of waves that are generally caused by significant movements of large bodies of water. When movements occur in tectonic plates that border or sit under bodies of water, those bodies of water are displaced and this causes a series of waves as the water resettles. When earthquakes are caused by significant shifts in tectonic plates the size of the waves produced can be significant as they were in the March 11th, 2011 tsunami. There is yet to be a resolution that can prevent the damage of a tsunami since these water waves cannot be stopped until they hit dry land; however, it is believed that sea walls can help to reduce the amount of damage that is caused by them. Unfortunately for the people of Japan this theory proved untrue. The Japanese city of Kamaishi City spent $1.5 billion to put together the largest sea wall in the world since Japan is situated near to the edge of numerous plates and earthquakes and tsunamis are a part of life for the Japanese. The city of Kamaishi City was also largely decimated by the March 2011 tsunami generated by the 9.0 magnitude earthquake. This incident goes to prove that as of yet there is no known method to prevent tsunamis and as such the only resolution is to retreat from the area of impact.
The Geographic Location of Japan
The Japanese archipelago lies on the joining of multiple tectonic plates, four to be exact: the Pacific, the Eurasion, Phillipine and North American Plates. When significant shifts occur in any of these plates earthquakes result and due to its lying on four joining plates Japanese citizens have come to expect these natural disasters as a part of normal life. In fact since Japan is surrounded by water the Japanese have also come to expect the following tsunamis and as such students in schools throughout Japan are not only given earthquake drills but they are also taught tsunami survival strategies as well. In the March 2011 9.0 magnitude earthquake it was the Pacific tectonic plate that shifted and slid under the North American plate to cause the significant rumbles that sent Japan in to a state of emergency.
What Does the March, 2011 Earthquake Mean for the Geography of the Planet?
While most of us understand what the impact of this 9.0 magnitude quake means for the immediate future of Japan, not many of us know what it means for the geography of the planet as a whole. When the Pacific plate shifted underneath the North American plate it actually moved the Japanese archipelago closer to the North American continent by 13 feet. It has also been noted that since the quake Japan has sunk two feet which resulted in significantly more damage from the tsunami as the coastline of Japan sunk lower. The shifting of the Japanese archipelago is not the only result of the quake though, in fact a much larger shift took place – the axis of the entire Earth was shifted as well. According to current data the massive earthquake which is considered to be one of the four largest recorded quakes since 1900, managed to shift the entire Earth’s axis by 6 and a half inches which resulted in a shortening of the day by 1.6 microseconds. As the Earth’s axis shifted the planet began to spin faster which resulted in the loss of 1.6 microseconds from the day. The March 2011 quake is not the only incidence of shaving time off the day, however, and the hysteria that is being generated by the media in relation to this shortening of the day neglects to mention this fact. The heart of the matter is that since 2004 there have been at least two natural disasters that have shaved time off the day by shifting the Earth.
Was the March, 2011 Japanese Earthquake the Biggest Quake Recorded to Date?
No. The largest magnitude earthquake ever recorded occurred in 1960 in Chile. The 1960 Chile earthquake occurred on May, 22 at 7:11pm UTC and measured in at a 9.5 on the Richter scale. The 1960 earthquake killed around 1,655 people injured around 3,000 and some 2,000,000 were left homeless. While the magnitude of this quake was larger than that in Japan in 2011 the number of people killed in the Japanese quake has far outweighed those killed in Chile already. The Chile quake caused a 1,000 km section of the fault to rupture over a few days, the largest rupture that has ever been reported as the result of a quake.
Remember that this is only an account of measured earthquakes. The technology necessary to measure earthquake magnitudes has only been around for the last century or so.
How Are Earthquakes Measured?
Earthquakes are measured through the use of a seismometer, a machine that senses motion in the Earth and a seismograph records that motion on paper so that research scientists can compare graphs to get an accurate reading of the amount of movement that has taken place. An earthquake’s magnitude is determined by looking at seismograph readings from various locations near to and far from the source of the quake. The magnitudes of earthquakes are quantified using the Richter scale. The Richter scale is a scale that goes from 1 to 10 that represents the oscillations that have been measured on the seismograph. Each division of the Richter scale differs from the last by a multiple of ten so that a quake that measures in at 7.0 is ten times bigger than a quake that measures in at 6.0 on the Richter scale. As stated above, the largest quake ever measured on the Richter scale was the 9.5 magnitude quake that hit Chile in 1960.
The Richter Scale
- Less than 2.0: These quakes are considered micro quakes and generally occur 8,000 times per year.
- 2.0 to 2.9: These quakes are considered minor quakes and are usually not felt but are recorded by seismologists. These types of quakes occur approximately 1,000 times per day.
- 3.0 to 3.9: These quakes are also considered minor quakes and are generally felt but are not usually large enough to cause damage. These types of quakes occur approximately 49,000 times a year.
- 4.0 to 4.9: These quakes are considered light quakes and while they do not generally produce large amounts of damage they are known for shaking items and producing rattling noises. Approximately 6,200 of these types of quakes occur yearly.
- 5.0 to 5.9: These quakes are considered moderate quakes and can cause damage to some structures with damage being more significant to poorly constructed buildings. There are approximately 800 of these types of quakes yearly.
- 6.0 to 6.9: These quakes are considered strong and can destroy structures within a radius of approximately 100 miles in areas that are well populated. Approximately 120 of these types of quakes occur yearly.
- 7.0 to 7.9: These quakes are considered major and can cause large amounts of damage over large areas of land. Approximately 18 of these types of quakes are measured yearly.
- 8.0 to 8.9: These quakes are considered great and can cause several hundreds of miles of damage. Approximately 1 of these types of quakes occurs yearly.
- 9.0 to 9.9: These quakes are also great and can cause significant devastation over several thousands of miles. Approximately 1 of these quakes occurs every 20 years.
- 10.0+: These quakes are considered massive and have never to date been recorded. Estimations predict that this type of quake could result in planet wide devastation and are unknown.
Is This the Beginning of the End?
Many people are significantly concerned about the occurrence of the 2011 Japanese earthquake, insinuation that it is the mark of the beginning of the end. What prompts this concern? For some it is the rumor that according to the Mayan calendar the world is doomed to end at the end of 2012, for others it is the plethora of natural disasters that seem to have plagued the planet lately and for others it is simply the intense magnitude of this last earthquake being something that has never been measured before. So is this the beginning of the end? There really is no indication that the March 2011 earthquake is a foreshadowing of anything to come, in fact looking back through the history of the continents it is highly unlikely that this earthquake is anything more than another shift of the tectonic plates that have been moving for billions of years. If the Earth were able to talk it is likely that the tectonic plates would tell of the extreme rumblings that tore apart the supercontinent of Pangea…and ask again and you would find out that the separation of the continents during this time was not the first time that the continents had experienced such a significant shift. For no, it is safe to assume that the March 2011 earthquake in Japan was nothing more than another shift in the ever moving tectonic plates and the ever changing Earth.Tagged With: